local io = require "io"
module("System", package.seeall)
--执行cmd 返回 stdout，true/false
function Exec(cmd)
    local f = io.popen(tostring(cmd))
    if not f then
        return nil, 1, "Command: "..cmd.." Exec false"
    end
    local ret = f:read("*all")
    return ret, f:close()
end